They have a corner. It is hit high towards the middle of your six-yard box, about four yards out from your line. There are bodies around, and nobody is directly in your path.
It is inside your six-yard box and you have a clear path, so it is yours. You called early, your defenders left it, and you caught it at the top of your jump, above everyone else. The corner is over.
A ball four yards out is too close to leave. From your line a header from there gives you almost no time to react. If you can reach a cross in the six-yard box, go and get it.
This is the worst of the three. You are off your line and not at the ball, so the goal is open behind you. Decide once. If you call it, go all the way.
Practise it with Take It At The Top, Crowded Box, Punch It.